October 20, 2010

Image representing 12 micrometer x 12 micrometer of artificial magnetic metamaterial where monopoles can be seen at each end of the Dirac strings, visible as dark lines. The dark regions correspond to magnetic islands where the magnetization is reversed. (Image courtesy of Paul Scherrer Institute)

(PhysOrg.com) -- Scientists have captured the first direct images of magnetic monopoles which were theoretically conceived by the British-Swiss physicist Dirac in the early 1930s who showed that their existence is consistent with the ultimate theory of matter  quantum theory.

According to the findings published in the leading scientific journal Nature Physics on 17 Oct 2010, the scientists were able to directly image the monopoles by using the highly intense x-ray radiation from the Swiss Light Source at the Paul Scherrer Institute.

A magnetic monopole is a hypothetical particle that is a magnet with only one single magnetic pole, says UCD Theoretical Physicist, Professor Hans-Benjamin Braun from the UCD School of Physics, who co-led the study with Dr Laura Heyderman from the Paul Scherrer Institute in Switzerland.

Some of the most important theories explaining how quantum matter behaves in the universe are based on their existence, but they have eluded direct imaging since they were first theoretically conceived in the 1930s.

We have for the first time directly imaged emergent monopoles inside an artificially created magnetic nano-metamaterial consisting of tiny magnets with a size of a couple of hundred nanometers, explains Professor Braun.

As Dirac predicted, the monopoles observed by the researchers come with `strings attached  the so called `Dirac strings which feed magnetic flux into the magnetic monopole in very much the same way a garden hose feeds water into a sprinkler.

The scientific team were able to capture the first direct images of the elusive monopoles together with their attached Dirac strings at room temperature.

An illustration of the monopoles shown as large spheres residing at the ends of a Dirac string. The dipoles are represented as dumbbells of magnetic charges and the Dirac string corresponds to a string of overturned dumbbells shown in dark.

The experiments show directly how north- and south pole separate from each other in an external field, creating the Dirac string in their wake, a fact that we were able to explain within a theoretical model says SFI funded UCD postdoc Dr Remo Hügli who together with Professor Braun designed the theory behind the experiment.

When the researchers examined the way the monopoles moved, they realized that each time they increased the applied magnetic field they triggered an avalanche of magnetization reversal of adjacent islands, similar to a row of toppling dominoes. These types of avalanches are not simply restricted to magnetic systems, but apart from their snowy and icy counterparts, they also may manifest themselves in sand, in earthquakes, and in stockmarket crashes.

The research, funded by Science Foundation Ireland and the Swiss National Science Foundation, may ultimately assist scientists working to understand how monopoles might have interacted in the early universe.

But, the findings may also have far more immediate applications in data transfer and storage. So far, only electric charges have been used in information processing and the use of magnetic charges could provide significant advantage in power consumption and speed.

Current computer hard discs store data magnetically, and their next generation will most likely be built from tiny isolated magnets precisely of the type investigated in this research. Thus, with improved understanding of the behaviour of magnetic monopoles scientists would be able to develop hard discs with considerably higher density data storage and faster data transfer speeds.

Initially conceived by the British-Swiss theoretical physicist Dirac in 1931, monopoles were proposed to occur as emergent quasiparticles in so called pyrochlore spin-ice systems by Castelnovo, Moessner and Sondhi in 2008.

Initial evidence for such monopoles and associated Dirac strings in pyrochlore systems at sub-Kelvin temperatures was reported in October 2009 led by Japanese, German, French and British scientists. The present research provides the first direct space evidence for monopoles and the associated Dirac strings. The artificially produced system investigated allows the manipulation of monopoles at room temperature, a considerable progress that opens the door for applications in data storage.

The research reported was led by Hans-Benjamin Braun at University College Dublin (UCD) and Laura Heyderman at the Paul Scherrer Institute (PSI). Hans-Benjamin Braun and his postdoc Remo Hügli supported by Science Foundation Ireland developed the theory behind the experiments and performed the numerical simulations of the system. Elena Mengotti, a PhD student at the Paul Scherrer Institute, supported by the Swiss National Science Foundation, performed the experiments. Frithjof Nolting and Arantxa Fraile Rodriguez from PSI are experts in magnetic spectroscopy and microscopy. They led the experimental work at the Swiss Light Source SLS.

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28 comments

These monopoles are as real monopoles, as the black holes in metamaterials are real black holes. They're rather toy models of monopoles and as such they were observed already many times inside of different materials.

No.. i think CTD1 has it right, we've seen these articles a few times over the last 3 years, there is observance of a metamaterial monopole that is really a sample that behaves like a monopole but is not really a monopole. It looks like a duck and quacks like a duck and we even observe it to understand how ducks walk but if you ask it what it is it says 'I ain't no duck.' Like the creation of Hawking radiation in a lab was not from forming a black hole or even a singularity. And as CTD1 referenced the creation of black holes in a lab aren't really black holes but they are suitable to study because they behave like black holes.

The creation a magnetic monopole would be fabulous there are applications beyond disk storage once you get creative ... high speed rails would suddenly become very effecient, and the possibility of a frictionless surfaces from two identical monopoles repelling each other...

It would mean, the rather common black holes with single jet or second jet deformed are sort of not only long sought monopoles, but the sought worm holes, too - we just didn't realize it. The same artifacts can serve as an evidence of CP symmetry violation at astronomical scale. Because many rotating objects in the Universe (including the Earth itself) are asymmetric in their shape, we can consider these objects as a degenerated monopoles, too. Radioactive atom nuclei are known to emanate radiation at only one direction, too. Actually it's possible, whole Universe is sort of monopole, because of Doppler shift of CMB noise.

It's interesting, the idea of deformed Earth was quite popular at medieval ages already. For example the fact, Christoph Columbus has chosen the north path for his travel into India was actually motivated his belief, this path is the shortest one.

Was Columbus the first unwilling propagator of monopole character of Universe? You can decide by now..

Actually such idea corresponds the black holes, merged with Einstein-Rosen bridge, i.e. area of more dense vacuum between them. If your idea is right, you should be able to prove CP violation and monopole around entangled electron, for example.

Whether such worm hole appears real or not, it depends on the distance in mass/energy density from observer. If the neck of dense vacuum connecting both black holes and/or particles will be sufficiently dense, it will reflect the outcoming light in total reflection mechanism, so it would behave like true worm black hole with event horizon and/or "dark string" predicted by quantum gravity theorists. If the observer would appear close or even inside of this neck, he may not observe anything. in opinion of Laura Mersini the well known CMB dark spot may be interpreted like hole into parallel universe. I'd consider the CMB dark spots rather as a view through areas of more dense vacuum (filled with dark matter) into more distant parts of Universe.

"It would mean, the rather common black holes with single jet or second jet deformed are sort of not only long sought monopoles, but the sought worm holes, too - we just didn't realize it."

Do you have any refs to published work that describes actual observations of a "one sided jet" from a particular object(AGN,neutron star, etc?) and describes the system as a gigantic magnetic monopole? What mass black hole are you referring to? Are you sure you fully understand the physics involved in a monopolar jet from *any* celestial body?

Are you sure you fully understand the physics involved in a monopolar jet from *any* celestial body?

Of course not. For example, so far at least four mechanism of jet suppression during particle collisions were proposed. Black holes are forming stable temporary products during their coalesce, the dynamics of which is quite complex.

As an example of black hole with pronounced jet asymmetry can serve the well known black hole sitting at the center of M87 galaxy.

It's not my intention at all. Worm holes are actually 4D (or higherdimensional) objects. For example, there you can find a computer simulation of dark strings in five dimensions as a consequence of Gregory-Laflamme instability:

Some of my skepticism of your comments arose from your frequent, seemly interchangeable use of "one-sided" jets and "asymmetric jets". They are clearly not interchangeable and I know of no AGNs (quasar, radio galaxy) where a claim of "one-sidedness" of the jets has been proven unequivocally. Given the complexities of the relevant physics,it seems that one-sided jets may exist in theory only. So now were left with SMBH with asymmetric jets that you now describe as monopoles or their proxy. That may be true in theory (or not), but I would need to see the particulars (they're important, you know).

3C 321 (in your link), has not been shown to have a monopolar jet, just very asymmetric jets. And, as you alluded to, M 87 has an obscured 22GHz and 44GHz counterjet: http://arxiv.org/...11v1.pdf

All particles with standing mass can be black holes. Anything become black hole if to compress it small enough and nobody actually know particles true sizes. So, it is possible if Hawkins evaporation is quantum mechanically forbidden. It can explain where the standing mass come from and how the light suddenly become trapped. And why the black holes seem sometimes so similar to them.

Space may be just our model of relations between objects and usually it is 3+1 dimensional. But it is just a model and the reality do not have dimensions. We create dimensions as we need in our models. But what is actually behind our usual 3+1 dimensions might be not metric.

..seemly interchangeable use of "one-sided" jets and "asymmetric jets". They are clearly not interchangeable..

Actually they're interchangeable often - you just don't know about it. The first findings presented at LHC actually consists in finding of small asymmetry in quark-gluon jets generated. Such finding is actually disappointment, because many physicists expected not only disappearance of one jet, but disappearance of both jets at the same moment:

The same dependence we can observe during formation of collapsars. The nebulae of less massive stars are formed with symmetric conical jets, when energy increases, their angles are becoming sharper and one of jets goes smaller, until it disappears completely. Before the true black hole is formed, the second jet goes down too.

So I really consider collapsars with asymmetric jets as an intermediate stage of true black holes without jets.

.. it is possible if Hawkins evaporation is quantum mechanically forbidden..

Actually the whole thing is not so difficult to imagine in context of relativity, if we realize, the massive black holes are formed with rotating torus, which is revolving like vortex ring.

The fast rotation of space-time around such vortex generates a strong axial drag known as a Lense-Thirring effect, which makes the escaping of light and particles through one of jets more difficult, then through the another one.

It's well known already, for such asymmetric flow of space-time the conditions for Hawking radiation are asymmetric, too - so that black hole jets around asymmetric black holes can be perceived as a pronounced case of Hawking radiation, too. You can read a bit about subtleties of photon sphere around Kerr holes and similar stuff. The physicists know about these effects quite well already for many years.

I presume, when black hole rotates even faster, an analogy of so called Widnall's instability is formed around torus, which results in fast space-time drag and "swallowing" of radiation around whole black hole.

In such way, the behaviour of massive black holes wouldn't differ from behaviour of fluid vortex very much, when limited speed of light and frame dragging (i.e. Lens-Thirring effect) is considered consistently.

We can think of the dirac model of monopoles as being a limit of the magnetic field of a solenoid as it gets very long and very thin. If you look at just one end of the solenoid, it looks like there's just a bunch of magnetic flux coming out of one central point, that in this model, represents the end of one of the strings. So mathematically, these dirac strings are infinitely thin, and infinitely flexible magnetic dipoles, and at each end of a string is a north and south pole.

It is only when you have one end of the string far away from the other, that the magnetic field starts to look like a monopole magnetic field (Latex code: B=g\frac{\mathbf{r}}{r^3}, g is the magnetic charge). The spin configurations in this line of research look like dirac strings because they physically realize a configuration of moving charges that looks like a really long and really thin solenoid. So what they are really to do is model the end of these strings as magnetic monopole "quasi-particles". Nothing in this research suggests that these monopoles are to be isolated beyond the confines of the material that they are studying, since they result from emergent properties of the material itself, and nothing else.

Depends on what you call a 'real' monopole, mattytheory. Seems to me that the fact there's a Dirac string involved doesn't detract from it being a monopole. Dirac strings were predicted alongside monopoles.

I bet if the string was cut youd get two sets of north and south monopoles.

Id say the monopoles are performing some sort of "suction" and keeping the ends individual. By the way you can't have one ending "sucking"...because you guessed it everything else ends up at the other end and that behaves like its "sucking". So you theorise that both ends arent "sucking" they just align...